1. Field of the Invention
The present invention relates to a system and method for data transmission/reception in a communication system. More particularly, the present invention relates to a system and method for data transmission/reception according to an operational state of a Mobile Station (MS) in a communication system.
2. Description of the Related Art
Next generation communication systems are being developed with an emphasis on providing services that can achieve high-speed large-capacity data transmission/reception for Mobile Stations (MSs). Representative examples of such next communication systems include a communication system using Institute of Electrical and Electronic Engineers (IEEE) 802.16 standards, and a communication system using 3rd Generation Partnership Project Long Term Evolution (3GPP LTE) standards. Both the IEEE 802.16 communication system and the 3GPP LTE communication system consider the mobility of an MS. Power consumption of the MS serves as an important factor of the entire system. Therefore, the IEEE 802.16 communication system supports a sleep mode operation between an MS and a Base Station (BS) in order to minimize power consumption of the MS, and the 3GPP LTE communication system supports a Radio Resource Control (RRC) state operation in order to minimize power consumption of the MS.
FIG. 1 illustrates sleep mode operations of a conventional IEEE 802.16 communication system.
The sleep mode operation illustrated in FIG. 1 corresponds to a sleep mode operation in the case of simultaneously using both a first service and a second service. As illustrated in FIG. 1, (A) corresponds to a sleep mode operation for providing the first service, (B) corresponds to a sleep mode operation for providing the second service, and (C) corresponds to the sleep mode operation of the MS corresponding to the sleep mode operations of the first service and the second service. As used herein, for the convenience of description, each of the frame intervals for providing the first service is called a “first service interval,” each of the frame intervals for providing the second service is called a “second service interval,” and each of the frame intervals in which the MS operates in the sleep mode is called an “MS sleep mode operation interval.”
The first service interval includes listening window intervals 110 and 114 and sleep window intervals 112 and 116, and the second service interval includes listening window intervals 120, 124, 128, 132, and 136 and sleep window intervals 122, 126, 130, and 134. As used herein, the listening window interval refers to an interval in which an MS operating in the sleep mode temporarily transits to an awake mode and monitors if a data packet to be transmitted/received through a wireless channel exists, and the sleep window interval refers to an interval for monitoring the wireless channel.
The MS sleep mode operation interval includes availability intervals 150, 154, 158, 162, and 166 and unavailability intervals 152, 156, 160, and 164. As used herein, each of the availability intervals refers to an interval that does not belong to any sleep window intervals related to the first service and the second service, and each of the unavailability intervals refers to an interval that belongs to sleep window intervals related to both the first service and the second service. The unavailability interval corresponds to a sleep interval of the MS, in which the MS stops supplying power to a transmission/reception module thereof and operates in a low power state.
FIG. 2 illustrates a RRC state operation of a conventional 3GPP LTE communication system.
Referring to FIG. 2, the RRC state includes an active state 210, a dormant state 212, an idle state 220, and a detached state 230.
The active state 210 refers to a state in which the MS is connected to the BS and transmits/receives data packets to/from the BS. The active state 210 includes the dormant state 212.
The dormant state 212 refers to a state in which the MS is connected to the BS but does not transmit or receive a data packet. An interval to which the dormant state 212 is applied corresponds to an unavailability interval in which data packets are not transmitted or received. Therefore, an MS in the dormant state 212 stops supplying power to a transmission/reception module thereof, thereby minimizing the power consumption.
The idle state 220 refers to a state in which an MS has been registered in the BS but is not connected to the BS yet. An MS in the idle state 220 can receive a paging message or other broadcasting information. Further, the MS in the idle state 220 scans reference signals transmitted from neighbor BSs, such as a Carrier to Interference and Noise Ratio (CINR) that can be used for measurement of a quality of a pilot channel signal, in preparation for handover.
The detached state 230 refers to a state in which communication between an MS and a BS has been interrupted, for example, a state in which the MS has been powered off or a state in which the MS is unable to receive a signal transmitted from the BS.
As noted from the above description referring to FIGS. 1 and 2, both the IEEE 802.16 communication system and the 3GPP LTE communication system support an operation of minimizing the power consumption of an MS. However, the interval in which the MS operates in the sleep mode, that is, an interval in which the MS does not transmit or receive a data packet, can be reduced according to a scheduling operation of the IEEE 802.16 communication system and the 3GPP LTE communication system. When the interval in which the MS does not transmit or receive a data packet is reduced, the interval in which the MS operates in the sleep mode is also reduced, so that it is possible to minimize the power consumption.
Meanwhile, when a battery of an MS has been exhausted, the MS is unable to perform communication. In an MS having insufficient battery power, minimization of power consumption is very important, even at the expense of transmission rate reduction, data transmission delay, etc. However, it is difficult to achieve minimization of battery power consumption, only by the operation for reducing the power consumption of an MS supported by the current IEEE 802.16 communication system and 3GPP LTE communication system.